foo = "1337"

puts foo.to_i

SafeString = String
String = Class.new(SafeString)

puts foo.to_i

class String
  def to_i
    1
  end
end

# recreate just to make sure
foo = "1337"

puts foo.to_i

String = SafeString

puts foo.to_i

# 1337
# test2.rb:8: warning: already initialized constant String
# 1337
# 1337
# test2.rb:23: warning: already initialized constant String
# 1337